Solvent softening shoe stiffener



7, 1956 w. H. HEATON ET AL 2,758,045

SOLVENT SOFTENING SHOE STIFFENER Filed Sept. 8, 1952 v INVENTORS Mum gym eqmzfzymb ,karl' Max. 7M 48,...

United StatesPatent z,7ss;;45

SOLVENT SOFTENING' SHOE STIFFENERL Walter H. .Heaton, Franklimand :Ronald: W. Morse, Newt0n,,Mass., assignors to BeckwithManufacturing Company, Dover, N. .H., a. corporation of New Hampshire ApplicationSeptember 8; 1952, Serial No. 308,366 3v fllaims.v (.Cl. 154 -46)v This invention comprises a new and" improved shoe stifiener of the solvent softening type having novel characteristics which particularly adapt it for use in unlined shoes. 7 p

Solvent softening box toes have been used with entire success for many years in the, manufacture of lined shoes where the box is locatedi'between the outer integument' of the upper and the lining and the lining is there.- fore interposed between the box and the last during many of the shoemaking operations to which the shoe is subjected. The solvent softening compounds with which such box toes are impregnated are very highly adhesive and necessarily so because it is important that the box I should be firmly bonded to the lining inorder to prevent the lining from sagging and dropping during the life of the shoe.

There is now, however, an insistent demand for a solvent softening box toe which may be used in unlined. shoes where the box toe must come indirect contact with the last. The industry has for a; long period struggled with the problem of providing a solvent softening box toe adapted for unlined shoesand so constructed and arranged as to prevent adhesive contact between the box and the last duringgthose operations in which the box is conditioned or activated, that is to say, While the box has been rendered soft, pliable and adhesive by solvent treatment. If any trace of the stiffening compound of the box reaches the surface of the last while in this condition, the box sticks to the last so that it is almost impossible to remove the shoe without tearing it to pieces. The present invention prevents that objectionable occurrence.

Many attemptshave been made to solve the problem bycoating the inner face of the box toe with a nonadhesive shield of rubber or wax or acomposite layer of such materials, but these attempts have, not been successful because the non-adhesive coating is likely to split orrupture when the temporarily softened toe is strained in the pulling over or lasting operations and when this occurs the stiifening compound seeps. through the crack and adheres to the last. with disastrous results.

The present invention is based on our discovery that the. difficulties heretofore encountered. are obviated by incorporating 'upon the inner: face ofthe *box toe athin preformed layer of polyethylene. uT liis material is highly non-adherent and has a very high factor of elongation besides being exceptionally tough in texture. Consequently the polyethylene layer is capable of stretching without danger of rupture even when the box toe is severely strained and distorted while incorporated in the upper and being drawn under pressure against the surface of the last. The polyethylene layer, moreover, is strictly non-toxic and antiseptic when in contact with the wearers foot. It is in itself highly flexible and elastic and so does not interfere in the slightest degree with the flexibility of the moistened and conditioned box toe Y t rim 2. as it is presented for the pulling over or lasting opera-' tions. It also retains its elastic characteristics when the box becomesstiifened in the, completed upper.

In successfully completing our invention it was necessary to solve a second problem, viz. the permanent bonding of the polyethylene film or ply to the body ofthe box toe. Polyethylene, as already noted,is highly nonadhesive but after extensivejresearch it was found that it could be successfully bonded to a, felt or textilebase by extruding it in thin sheet or film shape at a high temperature, laying it hot upon vthefibrous body material, and then immediately subjecting it to. pressure and cooling This procedure results in a secure and permanent bond entirely satisfactory for the purposes of box toe, ma l!!- facture.

These and other features of the invention will be best understood and appreciated from the following description of a preferred embodiment of the. box toe and of the process of its production as illustrated in the accompanying drawings in which:

Fig. 1 is a view in perspective suggestingfthe steps of manufacturing the box toe material in sheet form,

Fig. 2 is a view in perspective of a box toe blank showing the polyethylene ply. detached at one corner, and

Fig. 3 is a corresponding view of the blank as seen from its fibrous side, v

For purposes of illustration the invention is shown in its application to a solvent softening box toe of thecharacter described in U. 8'. Letters Patent No. 1,036,588,,

granted April 7, 1936, on an application of, S. P.. Lovell. The fibrous base material 10 comprises a porous felt, or. a waterlaid felt, or a woven or knitted fabric of single or double ply. For example, in making box toeblanks for, typical womens shoes it isappropriate to use as a fibrous base a true felt composed of 20% wool, cotton, and weighing about 4% 02s. per square yard. The base material is impregnated with asolvent softening stiffening compound which, for example, may comprise. a ture of nitrocellulose and boric acid as a substantially uniform dispersion which is porous and receptive of nitrocellulose solvents such as acetone, ethyl alcohol, diacetone alcohol or the like, or mixtures thereof. [15 ing such impregnating composition with the felt above identified, we produce a dried impregnated sheet weigh; ing about 15 /2 ozs. per square yard, 'that is, a finished, sheet containing about 11 ozs. or; impregnating solids. of which slightly more than one-half] is nitpocell'ulose, and slightly less than one-half is boric acid. The. efiect of the boric acid is to increase the porosity of the compound, render it substantially fireproof and. improve its, capability of being skived. In some cases it may be de sirable to add a small percentage of camphor to. the

stiffening compound to serve as, a plasticizing agent.

In Fig. 1 the polyethylene is represented as being extruded as a thin continuous sheet from the outlet nozzle 12 of an extruding machine provided witha die slit of the proper dimensions to extrude a sheet from 0.001 to 0.002; in thickness at a temperature of 5'Q0600- F. Polyethylene may be supplied, to. the extruding machine in the gran lar form in which i i yaveila le cemm r lly and if desired a coloring ingredient may be added so that the extruded sheet 11 will be tinted or colored and so indicate at once to the operator which side of the box toe is to be located in contact with the last.

As already noted it is important to extrude the polyethylene sheet 11 at a fairly high temperature in order to form a permanent bond with the fibrous base 10. At 500 F. the polyethylene issues as a preformed semisolid sheet from the die slit. The polyethylene sheet is led from the die slit immediately into contact with the base sheet 10 and then passed between a pair of pressure Patented Au 1,195

rollers 13 and 14 which press the two sheets firmly and progressively into contact and at the same time cool the polyethylene. A very firm and permanent bond is formed in this manner and the composite box toe material in sheet form may with little or no delay be wound into a coil 15.

In Fig. 2 is shown a box toe blank as it is died out from the sheet material produced in accordance with the process of Fig. 1. The blanks are died out in the proper shape and size for the unlined shoes in which they are to be incorporated. ,In Fig. 2 the polyethylene ply 11 is shown as separated from the fibrous base at one corner of the blank. This may be done with the exercise of sufficient force and care, and in stripping the polyethylene layer in this manner it will be found to carry with it the surface layer of fibres from the base 10. This is because the bond between the polyethylene and the fibre base is stronger than the bond between the components of the base itself.

The box toe blank is completed by skiving its transverse edge in an area 16 upon the fibrous base surface of the blank. In the skiving operation the polyethylene ply is not disturbed while the blank is reduced to a feather edge so that is will not show a transverse line across the tip of the finished 'shoe.

When the improved box toe of our invention is to be incorporated in a shoe upper, it is conditioned by the application of a suitable solvent such as acetone, ethyl alcohol or the like, and in this operation the blank is rendered soft, pliable and limp so that it may be readily and perfectly moulded in the upper to the last. It is also rendered moist and adhesive but nevertheless the polyethylene layer adheres permanently to the moist and softened fibrous base throughout any distortion to which the conditioned blank is subjected in the pulling over or lasting operations. In these operations the polyethylene layer is not only brought into severe frictional engagement with the wood of the last, but very severely stretched and strained. However, throughout all of such treatment the polyethylene layer maintains its integrity and acts as a complete and continuous shield between the body of the box toe and the wood of the last. The result is that while the fibrous surface of the box toe becomes permanently and adhesively bonded to the upper, there is no tendency whatever on the part of the polyethylene layer to stick to the wood of the last.

Our invention is useful also in its application to box toes which are distributed by the manufacturer in sealed containers while in a state of full or partial condition, that is to say, dampened and softened to some extent by solvent and therefore usable more immediately than blanks distributed in a fully dried state. The polyethylene layer applied as above explained remains intact and without impairment to its bond in such conditioned box toe blanks.

While we have referred specifically to one illustrative stiffening compound and to polyethylene as a material for the protective non-adherent ply, it would be within the scope of the invention to employ any equivalent compounds or materials.

A process of lasting the toes of unlined shoes in which is employed the stiffener herein disclosed is claimed in our co-pending application Ser. No. 488,384, filed February 15, 1955, now Patent No. 2,714,734 dated August 9, 1955.

Having thus disclosed our invention and described in detail an illustrative embodiment thereof and a preferred manner of producing it, we claim as new and desire to secure by Letters Patent:

1. A box toe stiffener of box toe configuration for use in an unlined shoe, consisting of a fibrous base impregnated throughout with a dry solvent-softening stiffening compound having latent adhesive characteristics, the compound being exposed on one face of the stiffener for adhesive attachment to an outer integurnent of an upper, and a thin tough elastic and integral ply of polyethylene of 0.001 to 0.002 inch thickness permanently united to the other face of the base and being highly elastic whereby it will stretch without rupturing when the impregnated fibrous base is strained While in softened condition during the lasting operation and will retain its elastic characteristics when the fibrous base is stiffened.

2. A box stiffener of box toe configuration for use in an unlined shoe, consisting of a base of fibrous sheet material impregnated throughout with a compound of dry nitrocellulose and boric acid having latent adhesive characteristics and being exposed on one surface of the base for bonding it to an outer integument of an upper, and a thin tough and elastic ply of polyethylene of 0.001 to 0.002 inch thickness permanently united to the other face of the base and having the property of stretching without rupturing when the impregnated fibrous base, incorporated in softened condition in a shoe upper, is strained during the lasting operation and of retaining its elastic characteristics when the compound is stiffened in the base in the toe portion of the upper.

3. A box toe stiffener of box toe configuration for use in an unlined shoe, consisting of a fibrous base impregnated throughout with a dry solvent-softening stiffening compound having latent adhesive characteristics, the compound being exposed on one face of the stiffener for adhesive attachment to an outer integument of an upper, and a thin tough elastic and integral ply of polyethylene permanently united to the other face of the base and being highly elastic whereby it will stretch without rupturing when the impregnated fibrous base is strained while in softened condition during the lasting operation and will retain its elastic characteristics when the fibrous base is stiffened.

References Cited in the file of this patent UNITED STATES PATENTS 559,311 Seaver Apr. 28, 1896 2,036,588 Lovell Apr. 7, 1936 2,219,700 Perrin et al. Oct. 29, 1940 2,391,445 Cohen Dec. 25, 1945 2,462,331 Myers Feb. 22, 1949 2,598,090 Yung et al. June 27, 1952 2,607,712 Sturken Aug. 19, 1952 2,625,499 Nebesar Jan. 13, 1953 FOREIGN PATENTS 731,650 France May 31, 1932 601,713 Great Britain June 11, 1948 831,311 Germany Feb. 11, 1952 

1. A BOX TOE STIFFENER OF BOX TOE CONFIGURATION FOR USE IN AN UNLINED SHOE, CONSISTING OF A FIBROUS BASE IMPREGNATED THROUGHOUT WITH A DRY SOLVENT-SOFTENING STIFFENING COMPOUND HAVING LATENT ADHENSIVE CHARACTERISTICS, THE COMPOUND BEING EXPOSED ON ONE FACE OF THE STIFFENER FOR ADHESIVE ATTACHMENT TO AN OUTER INTEGUMENT OF AN UPPER, AND A THIN TOUGH ELASTIC AND INTEGRAL PLY OF POLYETHYLENE OF 0.001 TO 0.002 INCH THICKNESS PERMANENTLY UNITED TO THE OTHER FACE OF THE BASE AND BEING HIGHLY ELASTIC WHEREBY IT WILL STRETCH WITHOUT RUPTURING WHEN THE IMPREGNATED FIBROUS BASE IS STRAINED WHILE IN SOFTENED CONDITION DURING THE LASTING OPERATION AND WILL RETAIN ITS ELASTIC CHARACTERISTICS WHEN THE FIBROUS BASE IS STIFFENED. 